The Syrian hamster is an especially suitable host for several infectious diseases. This laboratory is studying the inflammatory and immune response in various hamster infectious disease models which are ongoing in other investigators' laboratories. We are interested in any involvement (helpful or injurious) of acute phase reactants (female protein) and also wish to determine the isotype of antibody and correlate these factors with the resultant immunopathology. A persistent viral infection (LCM) is being studied in inbred hamster strains, which are either susceptible (MCH) or resistant (CB). In a persistent treponema model, hamsters have been found to be a suitable host for syphilis and yaws and protective immune immunoglobulins have been isolated and identified. One parasitic model also is being studied, as leishmania produces a chronic disease in hamsters similar to human infection; we have found evidence for glomerular immune complexes and also marked amyloid deposition.